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Array Detection (array + detection)
Kinds of Array Detection Selected AbstractsDetermination of uranium, iron, copper, and nickel from ore samples by MEKC using N,N,-ethylene bis(salicylaldimine) as complexing reagentELECTROPHORESIS, Issue 3 2008Muhammed Aslam Mirza Abstract An analytical procedure has been developed for the separation of dioxouranium(VI), iron(III), copper(II), nickel(II), cobalt(II), cobalt(III), palladium(II), and thorium(IV) by MEKC using N,N,-ethylene bis(salicylaldimine) (H2SA2en) as a complexing reagent with total runtime <4.5,min. SDS was used as micellar medium at pH,8 with sodium tetraborate buffer (0.1,M). An uncoated fused-silica capillary with an effective length of 50,cm×75,,m id was used with an applied voltage of 30,kV with photodiode array detection at 231,nm. Linear calibrations were obtained within 0.111,1000,,g/mL of each element with LODs within 37,325,ng/mL. The developed method was tested for analysis of uranium ore samples indicating its presence within 103,1789,,g/g with RSD within 0.79,1.87%. Likewise copper, nickel, and iron in their combined matrix were also simultaneously determined with RSD 0.4,1.6% (n,=,6). [source] Determination of glyoxal and methylglyoxal in the serum of diabetic patients by MEKC using stilbenediamine as derivatizing reagentELECTROPHORESIS, Issue 21 2007Muhammad A. Mirza Abstract An analytical method has been developed for the separation of glyoxal (Go), methylglyoxal (MGo), and dimethylglyoxal (DMGo) by MEKC using stilbenediamine (SD) as derivatizing reagent, separation time 6.5,min, SDS as micellar medium at pH,8, and sodium tetraborate (0.1,M) as buffer. Uncoated fused-silica capillary, effective length 50,cm×75,,m id; applied voltage 20,kV and photodiode array detection, were used. Calibration was linear within 0.02,150,,g/mL with detection limits 3.5,5.8,ng/mL. Go and MGo, observed for diabetic and healthy volunteers, were within 0.098,0.193,,g/mL Go and 0.106,0.245,,g/mL MGo with RSD 1.6,3.5 and 1.7,3.4%, respectively, in diabetics against 0.016,0.046,,g/mL Go and 0.021,0.066,,g/mL MGo with RSDs 1.5,3.5 and 1.4,3.6%, respectively, in healthy volunteers. Go and MGo in diabetics were also measured by standard addition and DMGo as an internal standard. Additives do not contribute significantly to Go and MGo matrix. [source] Data processing in metabolic fingerprinting by CE-UV: Application to urine samples from autistic childrenELECTROPHORESIS, Issue 6 2007Ana C. Soria Abstract Metabolic fingerprinting of biofluids such as urine can be used to detect and analyse differences between individuals. However, before pattern recognition methods can be utilised for classification, preprocessing techniques for the denoising, baseline removal, normalisation and alignment of electropherograms must be applied. Here a MEKC method using diode array detection has been used for high-resolution separation of both charged and neutral metabolites. Novel and generic algorithms have been developed for use prior to multivariate data analysis. Alignment is achieved by combining the use of reference peaks with a method that uses information from multiple wavelengths to align electropherograms to a reference signal. This metabolic fingerprinting approach by MEKC has been applied for the first time to urine samples from autistic and control children in a nontargeted and unbiased search for markers for autism. Although no biomarkers for autism could be determined using MEKC data here, the general approach presented could also be applied to the processing of other data collected by CE with UV,Vis detection. [source] Toxicology of a Microcystis ichthyoblabe waterbloom from Lake Oued Mellah (Morocco)ENVIRONMENTAL TOXICOLOGY, Issue 1 2002Brahim Sabour Abstract In the Lake Oued Mellah cyanobacteria waterblooms occur periodically in late spring and summer with Microcystis ichthyoblabe as the main bloom-forming species. In 1999, a heavy waterbloom of M. ichthyoblabe occurred during May June with a maximal biomass of 298 mg/l. During this period, several bloom samples were collected. The toxicity assessment was done by mouse and brine shrimp (Artemia) bioassays. Apart from the sample collected on 15/06/1999, all the other samples were toxic by mouse bioassay. The LD50 determined by intraperitoneal injection to mice during active cyanobacterial growth and decline phases were 518 and 1924 mgDW/kg respectively. Using Artemia bioassay, the 24hLC50 varied from 6.0 to 40.6 mg/ml and the 48hLC50 ranged from 2.8 to 18.2 mg/ml. The separation and identification of microcystin variants was performed by high performance liquid chromatography,photodiode array detection. Eleven toxins were separated and preliminarily identified as microcystin variants as they exhibit a typical UV spectra like the microcystin-LR standard. The quantification of total microcystins determined by enzyme-linked immunosorbent assay showed that the contents were varied between 0.1 and 0.76 ,g/g DW. © 2002 by Wiley Periodicals, Inc. Environ Toxicol 17: 24,31, 2002 [source] Detection and quantification of microcystins from cyanobacteria strains isolated from reservoirs and ponds in MoroccoENVIRONMENTAL TOXICOLOGY, Issue 1 2002B. Oudra Abstract In Morocco, the occurrence of toxic cyanobacteria blooms is confirmed in some water bodies used for recreational and/or as drinking water reservoirs. According to WHO recommendations, the establishment of a monitoring program for microcystins is a necessity. This paper presents toxicological studies of 19 toxic cyanobacteria strains of Microcystis, Synechocystis, Pseudanabaena, and Oscillatoria. These strains were isolated from various water bodies including natural lakes, reservoirs, and ponds located in central regions of Morocco. The isolation, culture, and biomass production of these strains was made on Z8 or BG13 media under laboratory controlled conditions. The hepatotoxicity of cyanobacterial lyophilized material was confirmed by mouse bioassays. The amount of microcystins produced by each strain was determined by the enzyme-linked immunosorbent assay (ELISA). The detection and identification of microcystin variants was performed by high performance liquid chromatography (HPLC) with photodiode array detection. Almost all strains showed medium to high toxicity, the estimated LD50 i.p mice bioassay ranged between 28 to 350 mg/kg body weight. The concentrations of microcystins varied between 2.16 to 944 ,g/g and 26.8 to 1884 ,g/g dry weight determined by ELISA and HPLC, respectively. The screening of bloom-forming and microcystin producer cyanobacteria strains in these fresh water bodies leads us to propose the need for the establishment of a survey of cyanobacteria and a cyanotoxin-monitoring program. © 2002 by Wiley Periodicals, Inc. Environ Toxicol 17: 32,39, 2002 [source] Metabolism of fluoranthene in different plant cell cultures and intact plantsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2000Marit Kolb Abstract The metabolism of fluoranthene was investigated in 11 cell cultures of different plant species using a [14C]-labeled standard. Most species metabolized less than 5% of fluoranthene to soluble metabolites and formed less than 5% nonextractable residues during the standardized 48-h test procedure. Higher metabolic rates were observed in lettuce (Lactuca sativa, 6%), wheat (Tricitum aestivum, 9%), and tomato (Lycopersicon esculentum, 15%). A special high metabolic rate of nearly 50% was determined for the rose species Paul's Scarlet. Chromatographic analysis of metabolites extracted from aseptically grown tomato plants proved that the metabolites detected in the cell cultures were also formed in the intact plants. Metabolites produced in tomato and rose cells from [14C]-fluoranthene were conjugated with glucose, glucuronic acid, and other cell components. After acid hydrolyses, the main metabolite of both species was 1-hydroxyfluoranthene as identified by gas chromatography,mass spectrometry and high-performance liquid chromatography with diode array detection. The second metabolite formed by both species was 8-hydroxy-fluoranthene. A third metabolite in tomatoes was 3-hydroxyfluoranthene. [source] Hard-modelled trilinear decomposition (HTD) for an enhanced kinetic multicomponent analysisJOURNAL OF CHEMOMETRICS, Issue 5 2002Yorck-Michael Neuhold Abstract We present a novel approach for kinetic, spectral and chromatographic resolution of trilinear data sets acquired from slow chemical reaction processes via repeated chromatographic analysis with diode array detection. The method is based on fitting rate constants of distinct chemical model reactions (hard-modelled, integrated rate laws) by a Newton,Gauss,Levenberg/Marquardt (NGL/M) optimization in combination with principal component analysis (PCA) and/or evolving factor analysis (EFA), both known as powerful methods from bilinear data analysis. We call our method hard-modelled trilinear decomposition (HTD). Compared with classical bilinear hard-modelled kinetic data analysis, the additional chromatographic resolution leads to two major advantages: (1) the differentiation of indistinguishable rate laws, as they can occur in consecutive first-order reactions; and (2) the circumvention of many problems due to rank deficiencies in the kinetic concentration profiles. In this paper we present the theoretical background of the algorithm and discuss selected chemical rate laws. Copyright © 2002 John Wiley & Sons, Ltd. [source] EFFECTS OF DIFFERENT MACERATION TIMES AND PECTOLYTIC ENZYME ADDITION ON THE ANTHOCYANIN COMPOSITION OF VITIS VINIFERA CV. KALECIK KARASI WINESJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2009HASIM KELEBEK ABSTRACT Kalecik karasi is an important red grape cultivar for winemaking in Turkey. The effect of three different maceration times (3, 6 and 12 days) and addition of pectolytic enzyme (2 and 4 g/hL) on the anthocyanin and chemical composition of Kalecik karasi wines were studied. High performance liquid chromatography-mass spectrometry coupled with diode array detection was used for analysis. Fourteen anthocyanin compounds were detected in wines. Major anthocyanins in all wines are malvidin-3-glucoside and its acylated esters. The results showed that increasing maceration time, especially with addition of enzymes, gives significant increases in anthocyanin contents. Moreover, the wines treated with enzymes had higher values in total phenolics, tannins, and color intensity than the control wines. PRACTICAL APPLICATIONS Anthocyanins are the most important polyphenols in red grapes and red wines with potential health benefits. Therefore, the first analysis of the anthocyanins contents of wine obtained from important turkish cv. Kalecik karasi using liquid-chromatography-mass spectrometry and the influence of different maceration times and addition of pectolytic enzyme on these important phenolic compounds are of interest for scientific literature, the wine industry as well as for the wine consumer. [source] Physicochemical, Nutritional, and Functional Characterization of Fruits Xoconostle (Opuntia matudae) Pears from Central-México RegionJOURNAL OF FOOD SCIENCE, Issue 6 2010Salvador H. Guzmán-Maldonado Abstract:, Xoconostle cv. Cuaresmeño (Opuntia matudae) has attracted domestic and international industry attention; however, variations of composition from xoconostle structures have not been evaluated. Industries discard the pulp (endocarp) and peel (pericarp) as wastes and utilize the skin (mesocarp), which is the edible portion. The physicochemical, nutritional, and functional characterization of structures from xoconostle pear from 3 major sites of production in Mexico were assessed. Skin yield ranged from 58% to 64% and was higher to that of peel (22% to 24%) and pulp (12% to 18%) yields. pH, °Brix, and acidity were similar among xoconostle structures. Total fiber showed by peel (18.23% to 20.37%) was 2-fold higher than that of skin. Protein and ether extract were higher in xoconostle pulp compared to that showed by peel and skin. Iron content of xoconostle peel (6 to 9.6 mg/100 g, DWB) was higher to that of skin and pulp and prickly pear pulp. Soluble phenols of peel (840 to 863 mg GAE/100 g, DWB) were almost similar to that of skin (919 to 986 mg GAE/100 g, dry weigh basis); meanwhile, ascorbic acid concentration of skin was 2-fold higher compared to that of peel. The phenolic fraction of xoconostle structures consisted of gallic, vanillic, and 4-hydroxybenzoic acids; catechin, epicatechin, and vanillin were also identified by high-performance liquid chromatography,didoe array detection (HPLC-DAD). Xoconostle peel showed higher antioxidant activity (TEAC) compared to that of skin (2-fold) and pulp (6-fold) of commonly consumed fruits and vegetables. The potential of xoconostle peel and pulp for the production of feed or food is promissory. Practical Application:, Outstanding nutritional and functional properties of xoconostle cv. Cuaresmeño fruits are demonstrated. Increased consumption could contribute positively to improve the diet of rural and urban consumers. The high fiber, mineral, and antioxidant components of xoconostle peel and pulp suggest that these fruit structures, which are currently discarded as waste, have promissory use as feed or food by industry. [source] Fast CE analysis of adrenergic amines in different parts of Citrus aurantium fruit and dietary supplementsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 16 2010Laura Mercolini Abstract A CE method has been developed for the simultaneous analysis of the adrenergic amines synephrine, octopamine and tyramine in Citrus aurantium (bitter orange) fruit extracts and in dietary supplements. The analytes were separated on a fused silica capillary (50,,m id, 40.0,cm effective length, 48.5,cm total length) using a BGE composed of phosphate buffer (pH 2.5, 50,mM) and applying a 30,kV potential. The samples were injected hydrodynamically at 50,mbar for 25,s. The use of photodiode array detection (,=195,nm) allowed the quantification of the analytes and the control of peak purity. The method has been fully validated, obtaining satisfactory values of precision and extraction yield. The analytes are extracted with water from the dried whole fruits or fruit parts (endocarp, mesocarp and exocarp) or from the commercial formulations and directly injected into the CE apparatus. The results obtained were satisfactory in terms of precision (RSD <,5.7%) and accuracy (recovery >,89%). Thus, the method has demonstrated to be suitable for the qualitative and quantitative determination of synephrine, octopamine and tyramine in C. aurantium extracts, for dietary supplement quality control and for food adulteration identification. [source] Direct characterization of aqueous extract of Hibiscus sabdariffa using HPLC with diode array detection coupled to ESI and ion trap MSJOURNAL OF SEPARATION SCIENCE, JSS, Issue 20 2009Inmaculada C. Rodríguez-Medina Abstract The phenolic fraction and other polar compounds of the Hibiscus sabdariffa were separated and identified by HPLC with diode array detection coupled to electrospray TOF and IT tandem MS (DAD-HPLC-ESI-TOF-MS and IT-MS). The H. sabdariffa aqueous extract was filtered and directly injected into the LC system. The analysis of the compounds was carried out by RP HPLC coupled to DAD and TOF-MS in order to obtain molecular formula and exact mass. Posterior analyses with IT-MS were performed and the fragmentation pattern and confirmation of the structures were achieved. The H. sabdariffa samples were successfully analyzed in positive and negative ionization modes with two optimized linear gradients. In positive mode, the two most representative anthocyanins and other compounds were identified whereas the phenolic fraction, hydroxycitric acid and its lactone were identified using the negative ionization mode. [source] Quantification of polyphenols with potential antioxidant properties in wines using reverse phase HPLCJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2008Neuza Paixão Abstract A RP-HPLC method with photodiode array detection (DAD) was developed to separate, identify and quantify simultaneously the most representative phenolic compounds present in Madeira and Canary Islands wines. The optimized chromatographic method was carefully validated in terms of linearity, precision, accuracy and sensitivity. A high repeatability and a good stability of phenolics retention times (< 3%) were obtained, as well as relative peak area. Also high recoveries were achieved, over 80.3%. Polyphenols calibration curves showed a good linearity (r2 >0.994) within test ranges. Detection limits ranged between 0.03 and 11.5 ,g/mL for the different polyphenols. A good repeatability was obtained, with intra-day variations less than 7.9%. The described method was successfully applied to quantify several polyphenols in 26 samples of different kinds of wine (red, rosé and white wines) from Madeira and Canary Islands. Gallic acid was by far the most predominant acid. It represents more than 65% of all phenolics, followed by p -coumaric and caffeic acids. The major flavonoid found in Madeira wines was trans -resveratrol. In some wines, (,)-epicatechin was also found in highest amount. Canary wines were shown to be rich in gallic, caffeic and p -coumaric acids and quercetin. [source] Determination of uric acid in plasma and allantoic fluid of chicken embryos by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2007Jana Mat, ková Abstract Capillary electrophoresis with diode array detection (DAD) was used to determine uric acid (UA) in chicken plasma and the allantoic fluid of chicken embryos. Complete separation of uric and ascorbic acids was attained in less than 10 min in the optimized BGE containing 60 mM MES + 30 mM Tris + 0.001% (w/v) polybrene (pH 6.1). The limit of UA detection (0.2 mg/L) was found to be low enough for sensitive analysis of native plasma and allantoic fluid samples. Range of linearity (1,200 mg/L), repeatability for peak area (CV <4.1%) and migration time (CV <2.5%), as well as recovery of UA from biological samples (97,100%), were found to be satisfactory. The method was applied to detect the elevated UA concentrations (hyperuricemia) in chicken embryos with induced unilateral renal agenesis. CE/DAD analysis of the chicken plasma can be carried out with a relatively small volume of samples (1 ,L). [source] Compositional changes induced by UV-B radiation treatment of common bean and soybean seedlings monitored by capillary electrophoresis with diode array detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 4 2007Giovanni Dinelli Abstract In this work, a new CE method with diode array detection (DAD) was developed for the monitoring and quantitation of flavonoids in different beans treated and untreated with UV-B radiation. Flavonoid concentration was monitored in UV-B-treated and untreated sprouts of three common beans (Zolfino ecotype, cv. Verdone, cv. Lingua di Fuoco) and one soybean (cv. Pacific). After acid hydrolysis of extracts, the CE-DAD method provides reproducible quantitative determinations of daidzein, glycitein, genistein, and kaempferol at ppm level in these natural matrices within a relatively short time (less than 16 min). Total flavonoid content determined by CE-DAD was 159 ± 8, 26 ± 2, 13 ± 1, and 1.3 ± 0.3 ,g/g fresh weight for untreated sprouts of Pacific soybean, Verdone bean, Zolfino bean, and Lingua di Fuoco bean, respectively. UV-B treatment caused no significant quantitative effect on Pacific soybean sprouts, whereas it enhanced the total isoflavone content by 1.5, 1.8, and 3.2-fold in Verdone, Zolfino, and Lingua di Fuoco beans, respectively. The proposed method shows (i) the potentialities of bean sprouts as a natural source of bioactive compounds (antioxidants); (ii) the technological role of UV-B treatment for sprout isoflavone enrichment; and (iii) the good capabilities of CE-DAD to monitor this process. [source] Simultaneous analysis of nine active components in Gegen Qinlian preparations by high-performance liquid chromatography with diode array detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2006Lihong Chen Abstract HPLC with diode array detection (HPLC/DAD) was employed to determine the quantities of puerarin, daidzin, daidzein, berberine, palmatine, coptisine, baicalin, baicalein, and glycyrrhizin in Gegen Qinlian preparations of three different pharmaceutical forms including decoction, dispensing granule and pill. The calibration curves for the nine bioactive components were linear in the given concentration ranges. The precision of the method was in the range of 0.2,5.0% (RSD), and the recoveries of this method were between 96.5 and 104.1%. The proposed method was applicable to analyze Gegen Qinlian preparations. [source] Simultaneous determination of carotenoids, tocopherols, and ,-oryzanol in crude rice bran oil by liquid chromatography coupled to diode array and mass spectrometric detection employing silica C30 stationary phasesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2005Wolfgang Stöggl Abstract Crude rice bran oil contains tocopherols (vitamin E), carotenoids (vitamin A), and phytosterols, which possess antioxidant activities and show promising effects as preventive and therapeutic agents. The aim of this work was to establish methods and to compare C18 and C30 silica stationary phases in order to separate and detect tocopherols, carotenoids, and ,-oryzanol in one single run. Comparing RP-LC on silica C18 and C30, higher resolution between all target compounds was obtained using the C30 stationary phase. Methanol was used as eluent and the elution strength was increased by the addition of tert -butyl methyl ether for highly hydrophobic analytes such as ,-oryzanol. Detection was accomplished by diode array detection from 200 to 500 nm. Absorbance maxima were found at 295 nm for tocopherols, 324 nm for ,-oryzanol, and 450 nm for carotenoids. Furthermore, compounds were characterized and identified on the basis of their UV-spectra. Both RP systems were coupled to MS (LC-MS) by using an atmospheric pressure chemical ionization interface. [source] Characterization via liquid chromatography coupled to diode array detector and tandem mass spectrometry of supercritical fluid antioxidant extracts of Spirulina platensis microalgaJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9-10 2005Jose A. Mendiola Abstract Spirulina platensis microalga has been extracted on a pilot scale plant using supercritical fluid extraction (SFE) under various extraction conditions. The extraction yield and the antioxidant activity of the extracts were evaluated in order to select those extracts with both the highest antioxidant capacity and a good extraction yield. These extracts were characterized using LC coupled to diode array detection (DAD) and LC coupled to mass spectrometry (MS) with two different interfaces, atmospheric pressure chemical ionization (APCI) and electrospray (ESI) which allowed us to perform tandem MS by using an ion trap analyzer. The best extraction conditions were as follows: CO2 with 10% of modifier (ethanol) as extraction solvent, 55°C (extraction temperature) and 220 bar (extraction pressure). Fractionation was achieved by cascade depressurization providing two extracts with different activity and chemical composition. Several compounds have been identified in the extracts, corresponding to different carotenoids previously identified in Spirulina platensis microalga along with chlorophyll a and some degradation products. Also, the structure of some phenolic compounds could be tentatively identified. The antioxidant activity of the extracts could be attributed to some of the above mentioned compounds. [source] A comparative study of several HPLC methods for determining free amino acid profiles in honeyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 9-10 2005José Luis Bernal Abstract A study of the viability of three derivatizing reagents for obtaining amino acid profiles in honey through high performance liquid chromatography (HPLC) is presented. A method using diode array detection based on a reaction with diethyl ethoxymethylene malonate (DEMM) and two other methods using fluorescence detection based on derivatization with fluorenylmethyl chloroformate (FMOC-Cl) and 6-aminoquinolyl- N -hydroxysuccinimidyl carbamate (AQC) have been developed. The three methods yield detection limits close to the ppb level, but vary in relation to other analytical characteristics. The use of methyl chloroformate derivatives allows the profile to be obtained with the greatest sensitivity within a short time frame. On applying such methods to honey samples of diverse botanical origin, we observe that the proline values obtained are always lower than those found using the official spectrophotometric method, thereby underlining the advisability of using HPLC methods to reduce uncertainty in these results. [source] Determination of cyprodinil and fludioxonil in the fermentative process of must by high-performance liquid chromatography,diode array detectionJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2008Luis Vaquero-Fernández Abstract BACKGROUND: A quantitative, selective and sensitive high-performance liquid chromatographic method is described for the analysis of new fungicides cyprodinil, fludioxonil and their commercial formulation Switch in model solutions of must and wine, as well as samples during alcoholic fermentation. A study of the dissipation of residues was carried out. RESULTS: The proposed method is based on liquid,liquid extraction (LLE) followed by high-performance liquid chromatography and diode array detection. Dichloromethane was the most appropriate solvent for extracting cyprodinil and fludioxonil in samples. Quality parameters of the proposed method presented good recovery (ca. 97% for almost all compounds) and precision (between 4.8% and 5.4%), and limits of quantification were lower than maximum residue limits (MRLs) in grapes. CONCLUSIONS: There is no matrix effect in the analysis of cyprodinil and fludioxonil. The application of the fermentative process on cyprodinil and fludioxonil fungicides causes a decrease in the concentrations of these compounds. This decrease is slightly higher, the higher the initial concentration, without observing the appearance of any product in degradation. Fludioxonil shows a higher reduction when the compounds are presented together in Switch. Copyright © 2008 Society of Chemical Industry [source] Evaluation of lignans and free and linked hydroxy-tyrosol and tyrosol in extra virgin olive oil after hydrolysis processesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2006Nadia Mulinacci Abstract We describe chemical hydrolytic procedures to evaluate the total amount of tyrosol and hydroxy-tyrosol free and/or linked to secoiridoidic molecules (acid hydrolysis). At the same time a rapid determination of the lignans in complex minor polar compound (MPC) extracts is proposed (alkaline hydrolysis). High-performance liquid chromatography/diode array detection (HPLC/DAD) and HPLC/MS were applied as reference methods to evaluate the quantitative results from the hydrolysis experiments. The optimized acid hydrolysis procedures were first applied to an oleuropein standard and then to MPC fractions extracted from several commercial extra virgin olive oils. The results confirm the applicability of the method, consisting in the acid hydrolysis of complex mixtures of secoiridoidic derivatives, to determine the antioxidant potential in terms of MPC. These data can contribute to forecasting the potential ageing resistance of an extra virgin olive oil in terms of antioxidant potency. Finally, alkaline hydrolysis allows confirmation and easy determination of the amount of lignans, especially in those MPC fractions which are particularly complex. Copyright © 2006 Society of Chemical Industry [source] Comparative study of six pear cultivars in terms of their phenolic and vitamin C contents and antioxidant capacityJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2003Andrea C Galvis Sánchez Abstract The main phenolic compounds in six pear cultivars were identified and quantified using high-performance liquid chromatography/diode array detection (HPLC/DAD) and HPLC/electrospray ionisation mass spectrometry (HPLC/ESIMS). Major quantitative differences were found in the phenolic profiles. The peel contained higher concentrations of chlorogenic acid, flavonols and arbutin than the flesh, where only chlorogenic acid was detected. Total phenolics ranged from 1235 to 2005 mg kg,1 in the peel and from 28 to 81 mg k g,1 in the flesh. Ascorbic acid and dehydroascorbic acid were detected in the peel, whereas only dehydroascorbic acid was present in the flesh. The ranges of vitamin C content were from 116 to 228 mg kg,1 in the peel and from 28 to 53 mg kg,1 in the flesh. The antioxidant capacity was correlated with the content of chlorogenic acid (r = 0.46), while ascorbic acid made only a small contribution to the total antioxidant capacity of the fruit. Copyright © 2003 Society of Chemical Industry [source] High-performance liquid chromatography with diode array detection coupled to electrospray time-of-flight and ion-trap tandem mass spectrometry to identify phenolic compounds from a Cistus ladanifer aqueous extractPHYTOCHEMICAL ANALYSIS, Issue 4 2010S. Fernández-Arroyo Abstract Introduction , Cistus ladanifer is an aromatic shrub that is widespread in the Mediterranean region. The labdanum exudate is used in the fragrance industry and has been characterised. However, there is not enough information about the phenolic content of the raw plant, the aerial part of it being a very rich source of bioactive compounds. Objective , Characterisation of the bioactive compounds of the raw plant and its aerial parts. Methodology , High-performance liquid chromatography with diode array and electrospray ionisation mass spectrometric detection was used to carry out the comprehensive characterisation of a Cistus ladanifer shrub aqueous extract. Two different MS techniques were coupled to HPLC: time-of-flight mass spectrometry and tandem mass spectrometry. Results , Many well-known compounds present in Cistus ladanifer were characterised, such as flavonoids, phenolic acids, ellagitanins, hexahydroxydiphenoyl and derivatives, and other compounds. Conclusion , The method described simultaneously separated a wide range of phenolic compounds and the proposed characterisation of the major compounds of this extract was carried out. It is important to highlight that, to our knowledge, this is the first time that a Cistus ladanifer aqueous extract from the raw plant has been characterised. Copyright © 2009 John Wiley & Sons, Ltd. [source] A survey of sesamin and composition of tocopherol variability from seeds of eleven diverse sesame (Sesamum indicum L.) genotypes using HPLC-PAD-ECDPHYTOCHEMICAL ANALYSIS, Issue 4 2008Kelly S. Williamson Abstract The objective of this study was to determine the composition and content of sesamin and desmethyl tocopherols such as , -tocopherol (,T), , -tocopherol (,T) and , -tocopherol (,T) in seeds of sesame (Sesamum indicum L.) for 11 genotypes conserved in the United States Department of Agriculture (USDA), Agricultural Research Service (ARS) and Plant Genetic Resources Conservation Unit (PGRCU) in Griffin, Georgia, USA. Seed accessions studied were collections from eight countries worldwide, including one landrace from Thailand and two cultivars from Texas, USA. Novel methodologies and analytical techniques described herein consisted of reverse-phase high-performance liquid chromatography (HPLC) connected in series with two detection systems specific for each analyte class. Photodiode array detection was employed for sesamin analysis and electrochemical array detection was used in the determination of tocopherols. A preliminary study was conducted to assess sesamin levels in 2003 and tocopherol levels in 2004 from sesame seed samples conserved at the USDA, ARS and PGRCU. In 2005, sesame seed samples were grown, harvested and evaluated for sesamin as well as tocopherol levels. The overall results (n = 3) showed that sesamin, ,T, ,T and ,T levels were 0.67,6.35 mg/g, 0.034,0.175 µg/g, 0.44,3.05 µg/g and 56.9,99.3 µg/g respectively, indicating that the sesame seed accessions contained higher levels of sesamin and ,T compared with ,T and ,T. Statistical analysis was conducted and significant differences were observed among the 11 different sesame genotypes. This suggests that genetic, environmental and geographical factors influence sesamin and desmethyl tocopherol content. Copyright © 2007 John Wiley & Sons, Ltd. [source] Reversed-phase HPLC-ESI/MS analysis of birch leaf proanthocyanidins after their acidic degradation in the presence of nucleophilesPHYTOCHEMICAL ANALYSIS, Issue 5 2007Maarit Karonen Abstract Mountain birch leaves contain large amounts of structurally variable polymeric proanthocyanidins. Their isolation procedure was enhanced by the addition of liquid,liquid extractions prior to column chromatography over Sephadex LH-20. Isolated polymeric proanthocyanidins were depolymerised by acid-catalysis in the presence of benzyl mercaptan or phloroglucinol in order to study their composition. The resulting degradation products, flavan-3-ols and flavan-3-ol adducts, were analysed with reversed-phase high-performance liquid chromatography using UV photodiode array detection for quantification and electrospray ionisation mass spectrometry for identification. The results showed that polymeric proanthocyanidins contained (epi)gallocatechins and (epi)catechins as the extension units and, mainly, (+)-catechin as the terminal unit. The mean degree of polymerisation was found to be 26 based on thiolysis and 31 based on phloroglucinol degradation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Analysis of Rhizoma Polygoni Cuspidati by HPLC and HPLC-ESI/MSPHYTOCHEMICAL ANALYSIS, Issue 5 2007Tao Yi Abstract An HPLC method with photodiode array detection (PAD) and ESI/MS detection was developed for the qualitative and quantitative analysis of the major chemical constituents of the dried rhizome of Polygonum cuspidatum Sieb. et Zucc. (Rhizoma Polygoni Cuspidati; Chinese name Hu-Zhang). Based on the chromatographic separation on an Altima C18 column using 0.5% aqueous acetic acid and acetonitrile as the mobile phase, nine compounds, including stilbenes, stilbene glucosides, anthraquinones and anthraquinone glucosides, were identified by online ESI/MS analysis and seven were quantified by HPLC-PAD. A full validation of the method including sensitivity, linearity, repeatability and recovery was conducted. Linear calibration was achieved over the concentration range 1,200 mg/L with R2 > 0.999, whilst the limits of detection ranged from 0.51 to 1.57 ng. Repeatability was evaluated by intra- and inter-day assays and the RSD value was within 1.79%. Recoveries of the quantified compounds were within the range 96.0,100.1% with RSD values of less than 2.2%. Five samples of Rhizoma Polygoni Cuspidati from different regions were analysed using the developed method. The major constituents piceid, resveratrol, emodin-8- O - , - d -glucoside and emodin were selected to provide an index for the quality assessment of the herbal drug. Copyright © 2007 John Wiley & Sons, Ltd. [source] A high-throughput monolithic HPLC method for rapid Vitamin C phenotyping of berry fruitPHYTOCHEMICAL ANALYSIS, Issue 5 2006Paul G. Walker Abstract A rapid method for the quantification of ,ascorbic acid (1) in berry fruit by HPLC with photodiode array detection is presented. ,Ascorbic acid was resolved on a C18 monolithic column with aqueous buffer, after which the column was washed with acetonitrile to remove lipophilic compounds prior to re-equilibration for analysis of the next sample. Using the monolithic column format with high mobile phase flow rates, the entire separation, wash and re-equilibration were achieved in 3 min. With the exception of gooseberry (Ribes uva-crispa), for which an interfering compound co-eluted, concentrations of 1 could be determined in a wide range of berry fruits after extraction in metaphosphoric acid without further sample preparation. Using this extraction method, recoveries of 1 in excess of 85% were achieved. Fruit or juice extracts were stable in 5% metaphosphoric acid for at least 4 h and stability could be extended to longer than 150 h by the addition of the reducing agent tris(2-carboxethyl)phosphine hydrochloride. Following validation, the method was utilised for the phenotyping of fruit in a Scottish Crop Research Institute (SCRI) Ribes nigrum L. breeding population of 300 individuals. An improved extraction method allowed extraction, quantification of 1 and data analysis to be undertaken in less than one working week. Copyright © 2006 John Wiley & Sons, Ltd. [source] Isolation and characterisation of selected germander diterpenoids from authenticated Teucrium chamaedrys and T. canadense by HPLC, HPLC-MS and NMRPHYTOCHEMICAL ANALYSIS, Issue 4 2006P. Ramnathan Sundaresan Abstract Teucrium species, such as germander, are rich in neo -clerodane diterpenoids and have been used in traditional folk medicine for their stimulant, diuretic, antipyretic and antiseptic properties. However, the furano neo -clerodane diterpenoids present in germander have been implicated in the in vivo hepatotoxicity of this botanical. In this study, authenticated germander (Teucrium chamaedrys L. and Teucrium canadense L.) was used as the source material. Methanol extracts of powdered plant material were prepared and analysed by HPLC using Synergi® Max-RP columns with monitoring at 220 nm. Limited amounts of teucrin A and other diterpenoid standards were analysed on a Synergi Max-RP column in order to determine their retention times and to generate calibration curves. The same standards were subjected to concurrent mass spectral analysis. Teucrin A and diterpenoids such as dihydroteugin, teuflin, teuflidin and teucvidin were tentatively identified in the plant extracts by HPLC-MS and 1H-NMR experiments. For the isolation of teucrium diterpenoids on a semipreparative scale, a solid-phase extraction method was developed for the first time using styrene divinylbenzene and strata-X sorbents for teucrin A and teuflin, respectively. Semi-preparative HPLC of the methanol extract of the powdered aerial parts of Teucrium plants was carried out on a semipreparative Synergi Max-RP column with photodiode array detection in order to confirm the identities of some diterpenoids by HPLC-MS and NMR. Copyright © 2006 John Wiley & Sons, Ltd. [source] Determination of diarylheptanoids from Alpinia officinarum (lesser galangal) by HPLC with photodiode array and electrochemical detection,PHYTOCHEMICAL ANALYSIS, Issue 4 2005Zhihua Liu Abstract Normal-phase column chromatography followed by semi-preparative reversed-phase HPLC has been used to isolate, from the rhizomes of Alpinia officinarum, five diarylheptanoids identified as 5-hydroxy-7-(4,-hydroxy-3,-methoxyphenyl)-1-phenyl-3-heptanone, 5-methoxy-7-(4,-hydroxy-3,-methoxyphenyl)-1-phenyl-3-heptanone, 7-(4,-hydroxyphenyl)-1-phenylhept-4-en-3-one, 7-(4,-hydroxy-3,-methoxyphenyl)-1-phenyl-hept-4-en-3-one, 1,7-diphenylhept-4-en-3-one. The levels of these five diarylheptanoids in root material were determined quantitatively by HPLC with UV detection and the assay methods so developed were simple, rapid and accurate. Four of the diarylheptanoids could also be detected by HPLC with electrochemical detection (ECD) in the oxidative mode, and ECD was found to have a higher sensitivity than photodiode array detection. Copyright © 2005 John Wiley & Sons, Ltd. [source] Identification and quantification of galloyl derivatives, flavonoid glycosides and anthocyanins in leaves of Pistacia lentiscus L.PHYTOCHEMICAL ANALYSIS, Issue 2 2002A. Romani Abstract Separation, identification and quantification of polyphenols was carried out on leaves of Pistacia lentiscus L., an evergreen member of the family Anacardiaceae, using semi-preparative HPLC, HPLC-photodiode array detection and HPLC-MS analysis, together with 1H- and 13C NMR. Three major classes of secondary metabolites were detected: (i) gallic acid and galloyl derivatives of both glucose and quinic acid; (ii) flavonol glycosides, i.e. myricetin and quercetin glycosides; and (iii) anthocyanins, namely delphinidin 3- O -glucoside and cyanidin 3- O -glucoside. Low amounts of catechin were also detected. The concentration of galloyl derivatives was extremely high, representing 5.3% of the leaf dry weight, and appreciable amounts of myricetin derivatives were also detected (1.5% on a dry weight basis). These findings may be useful in establishing a relationship between the chemical composition of the leaf extract and the previously reported biological activity of P. lentiscus, and may also assign a new potential role of P. lentiscus tissue extracts in human health care. Copyright © 2002 John Wiley & Sons, Ltd. [source] High-performance liquid chromatography with electrospray ionisation mass spectrometry and diode array detection in the identification and quantification of the degradation products of calix[4]arene crown-6 under radiolysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2004C. Lamouroux The extraction of 135Cs from high-activity liquid waste, arising from reprocessing of spent nuclear fuel, can be achieved by using calix[4]arene crown-6 compounds. The radiolytic degradation of di(n-octyloxy)calix[4]arene crown-6 (octMC6), in aliphatic or aromatic solvent in contact with 3 M nitric acid, was studied by high-performance liquid chromatography directly coupled to electrospray ionisation mass spectrometry (LC/ESI-MS). More than 50 distinct degradation products were observed, and about 30 of these were identified. These compounds can be assigned to three categories, namely, products of reactions involving radical cleavage or addition, of oxidation reactions, or of aromatic substitution reactions. The major product, corresponding to substitution by an NO2 group, was quantified by external standard calibration using a purified synthetic sample. Despite the observation of all these degradation compounds, octMC6 appears to be remarkably stable under these drastic conditions, combining hydrolysis (HNO3 3,M) and an extreme exposure to radiolysis (106,Gy). Less than 35% degradation of octMC6 was observed in aromatic solvent under these conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||||||||